Printed with permission of The Institute of Pure and Applied Physics (IPAP)

JAPANESE JOURNAL OF APPLIED PHYSICS
Part2

Abstracts of Express Letters
Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 445–L 447
Part 2, No. 5A, 1 May 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 497–L 498
Part 2, No. 5B, 15 May 2003
©2003 The Japan Society of Applied Physics

High-Quality AlN by Initial Layer-by-Layer
Growth on Surface-Controlled 4H−SiC(0001)
Substrate

InGaN-Based Single-Chip Multicolor
Light-Emitting Diodes

1,*

1,2

Norio ONOJIMA , Jun SUDA

1and Hiroyuki MATSUNAMI

Takashi AZUHATA*, Takefumi HOMMA, Yoshikazu ISHIKAWA and
ShigeFusa CHICHIBU1(Received March 24, 2003; accepted for publication April 1, 2003)(Received April 7, 2003; accepted for publication April 14, 2003)

The initial layer-by-layer growth of AlN was realized on a surfacecontrolled 4H–SiC(0001) substrate using plasma-assisted molecular-beam
epitaxy (PA-MBE). To achieve initial two-dimensional (2D) growth, thecontrol of SiC surface chemistry is very important as well as that of surface flatness. The effect of SiC preparation on the surface structure andchemical composition was investigated by using reflection high-energy
electron diffraction (RHEED) and in situ X-ray photoelectron spectroscopy(XPS). The initial growth mode of AlN was strongly influenced by the removal of residual oxygen atoms from the SiC surface. Symmetrical andasymmetrical X-ray rocking curve (XRC) measurements revealed that initial 2D growth was essential to obtain the excellent crystalline quality of
AlN layer. [DOI:10.1143 / JJAP.42.L445]
KEYWORDS: AlN, SiC, MBE, surface control, RHEED intensity oscillation, in-plane misorientation

A light-emitting diode (LED) driving technique to realize single-chip
multicolor LEDs was proposed. The technique utilizes one of the characteristics of InGaN-based visible LEDs, the current-induced spectral blueshift. By applying pulsed current, which had two pulses of different amplitude in a cycle, to an InGaN single-quantum-well green LED, the lightof two wavelengths corresponding to bluegreen and green was emitted from the same point, and the emission color of the LED was controlled continuously from bluegreen to green by adjusting only the pulse
widths. [DOI:10.1143 / JJAP.42.L497]
KEYWORDS: InGaN, single chip, multicolor, LED, spectral blueshift,pulsed current
Department of Materials Science and Technology, Hirosaki University, Hirosaki, Aomori 036-8561,
Japan
1 Institute of Applied Physics and Graduate School of Pure and Applied Sciences, University ofTsukuba, Tsukuba, Ibaraki 305-8573, Japan* E-mail address: azuhata@cc.hirosaki-u.ac.jp

1 Department of Electronic Science and Engineering, Kyoto University, Sakyo-ku, Kyoto
606-8501, Japan
2 Nanostructure and Material Property, PRESTO, Japan Science and Technology Corporation (JST),
Kawaguchi, Saitama 332-0012, Japan* E-mail address: onojima@matsunami.kuee.kyoto-u.ac.jp

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 448–L 450
Part 2, No. 5A, 1 May 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 499–L 501
Part 2, No. 5B, 15 May 2003
©2003 The Japan Society of Applied Physics

Digital Sorting of Flow-through Droplet Phase
Microfluid

Magnetic Tunnel Junction (MTJ) Patterning for
Magnetic Random Access Memory (MRAM)
Process Applications

Jeung Sang GO* and Shuichi SHOJI(Received March 7, 2003; accepted for publication April 2, 2003)

The in-plane digital sorting of the multiphase microfluid flow ispresented in the laminar flow regime. It is achieved by manipulating
the pitch of alternate microfluid flow and delay distance resulting frompassing through special microchannels. The theoretical analysis derives
delay distance. For experimental evaluation, a characteristic in-plane microchannel is fabricated by using micromachining. The pitch of the alternate microfluid flow is controlled. Digital sorting is demonstrated byusing the immiscible droplet phase fluids. Also, the dynamic behavior ofthe droplet phase microfluids is measured by the particle image velocimetry (micro-PIV) and characterized qualitatively and qualitatively.
[DOI:10.1143 / JJAP.42.L448]
KEYWORDS: digital sorting, droplet phase, alternate fluid, delay distance, micro-PIV
Department of Electronics, Information & Communication Engineering, Waseda University,
3-4-1 Ohkubo, Shinjuku-ku, Tokyo 169-8555, Japan* Corresponding author. E-mail address: s_gjs@shoji.comm.waseda.ac.jp

Kiyokazu NAGAHARA1,2, Tomonori MUKAI1,2, Nobuyuki ISHIWATA2,
Hiromitu HADA1,2 and Shuichi TAHARA1,2(Received April 2, 2003; accepted for publication April 4, 2003)

We have developed a top free type magnetic tunnel junction (MTJ)
patterning technique that involves tunnel barrier etching with enoughtime margins for chemical assisted ion etching (CAIE). The approximately
1nm thick tunnel barrier enables stopping the etching process in a shorter time margin. We have found that no aluminum-oxide barrier shorting by re-deposition occurred in chlorine based CAIE, when the etching
depth into anti-ferromagnetic IrMn layer was less than 5nm. The magnetoresistance (MR) ratio of the whole MTJ patterns reached 35% on a
6-inch wafer. The time margin of the etching was 120s, which is longenough for an magnetic random access memory (MRAM) process.
[DOI:10.1143 / JJAP.42.L499]
KEYWORDS: magnetic tunnel junction, reactive ion etching, MRAM,
tunnel barrier
1 MRAM Spintronics R&D Center, R&D Association for Future Electron Devices,
1120 Shimokuzawa, Sagamihara 229-1198, Japan
2 Silicon System Research Laboratories, NEC Corporation, 1120 Shimokuzawa, Sagamihara229-1198, Japan

JSAP International No.9 (January 2004)15

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 502–L 504
Part 2, No. 5B, 15 May 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 565–L 567
Part 2, No. 6A, 1 June 2003
©2003 The Japan Society of Applied Physics

Highly Efficient Room Temperature Spin
Injection in a Metal-Insulator-Semiconductor
Light-Emitting Diode

Growth of Bulk GaN Single Crystals Using
Li-Na Mixed Flux System

Pol Van DORPE*, Vasyl F. MOTSNYI1, Mayke NIJBOER,
Etienne GOOVAERTS1, Viacheslav I. SAFAROV2, Jo DAS, Wim Van ROY,
Gustaaf BORGHS and Jo De BOECK(Received March 31, 2003; accepted for publication April 8, 2003)

We demonstrate highly efficient spin injection at low and room
temperature in an AlGaAs/ GaAs semiconductor heterostructure froma CoFe/ AlOX tunnel spin injector. We use a double-step oxide deposition for the fabrication of a pinhole-free AlOX tunnel barrier. The measurements of the circular polarization of the electroluminescence in the
Oblique Hanle Effect geometry reveal injected spin polarizations of atleast 24% at 80K and 12% at room temperature.
[DOI:10.1143 / JJAP.42.L502]
KEYWORDS: spin injection, spintronics, room temperature, tunnel
barrier

Masanori MORISHITA, Fumio KAWAMURA, Tomoya IWAHASHI,
Masashi YOSHIMURA, Yusuke MORI and Takatomo SASAKI(Received March 31, 2003; accepted for publication April 21, 2003)

We found the yield of GaN grown in a Li-Na flux system to be muchhigher than that grown in Na flux. Nitrogen dissolution seemed to increase with Li in solution, which promotes the growth of GaN crystals.
In this paper, we report that the yield of GaN and habit modifications
greatly depend on the composition of the Li-Na flux system and that
GaN can be grown in a pure Li flux at about 50atm.
[DOI:10.1143 / JJAP.42.L565]
KEYWORDS: GaN, flux method, single crystal, high pressure, bulk,
LPE, nitrogen vacancy, habit modification
Department of Electrical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871,
Japan

Interuniversitary MicroElectronics Center (IMEC), Kapeldreef 75, B-3001 Leuven, Belgium
1 University of Antwerpen-UIA, Universiteitsplein 1, B-2610 Antwerpen, Belgium
2 Groupe de Physique des Etats Condensés (GPEC), Département de Physique,
Faculté des Sciences de Luminy, 13288 Marseille, France* E-mail address: pvandorp@imec.be

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 505–L 507
Part 2, No. 5B, 15 May 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 568–L 571
Part 2, No. 6A, 1 June 2003
©2003 The Japan Society of Applied Physics

Behavior of Impurity Ion Velocities during thePulsed Poloidal Current Drive in the Madison
Symmetric Torus Reversed-Field Pinch

Self-Tailored One-Dimensional ZnO Nanodot
Arrays Formed by Metalorganic Chemical
Vapor Deposition

Hajime SAKAKITA*, Darren CRAIG1, Jay K. ANDERSON1, Ted M. BIEWER2,Stephen D. TERRY2, Brett E. CHAPMAN1, Daniel J. DEN-HARTOG1 andStewart C. PRAGER1

Sang-Woo KIM*, Masaya UEDA, Teruhisa KOTANI, Shizuo FUJITA1 andShigeo FUJITA(Received April 11, 2003; accepted for publication April 18, 2003)(Received March 25, 2003; accepted for publication April 9, 2003)

One-dimensional ZnO nanodot arrays have been realized by metalWe report on passive measurements of impurity ion velocities during
the pulsed poloidal current drive (PPCD) in the Madison Symmetric Torus
reversed-field pinch. During PPCD, the electron temperature increased
and a sudden reduction of magnetic fluctuations was observed. For thischange, we have studied whether plasma velocity is affected. Plasma rotation is observed to decrease during PPCD. From measurements of line
intensities for several impurities at 10 poloidal chords, it is found that the
impurity line emission shifts outward. The ion temperature of impurities
is reasonably connected to that measured by charge exchange recombination spectroscopy from core to edge. [DOI:10.1143 / JJAP.42.L505]
KEYWORDS: plasma velocity, ion temperature, impurity emission,equilibrium reconstruction, pulsed poloidal current
drive, reversed field pinch
Energy Electronics Institute, National Institute of Advanced Industrial Science and Technology(AIST), 1-1-1 Umezono, Tsukuba 305-8568, Japan
1 Department of Physics, University of Wisconsin-Madison, 1150 University Avenue, Madison
53706, U.S.A.
2 Princeton Plasma Physics Laboratory, Princeton University, P.O.Box 451, Princeton 08543-0451,
U.S.A.
* E-mail address: h.sakakita@aist.go.jp

16

JSAP International No.9 (January 2004)

organic chemical vapor deposition on SiO2 substrates patterned by focused ion beam (FIB). Especially for the lines with the depth of 5nm andthe length of 0.7, 1.3 or 1.7µm, one, two or three nanodots, respectively, of fairly uniform size 6-nm height and 80-nm width are symmetricallyaccommodated in a line. These phenomena are translated as ``self-tailoring’’ of ZnO nanodots, i.e., where the nanodots will be is predetermined
before the growth and is arbitrarily controlled by the nanopatterns.
This can be a promising technique to build nanostructure blocks for nanoscale device applications. [DOI:10.1143 / JJAP.42.L568]
KEYWORDS: ZnO, one-dimensional, nanodot arrays, self-tailoring,
MOCVD, FIB, SiO2
Department of Electronic Science and Engineering, Kyoto University, Sakyo-ku, Kyoto 606-8501,
Japan
1 International Innovation Center, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan* E-mail address: swkim@fujita.kuee.kyoto-u.ac.jp

Part2

Abstracts of Express Letters

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 625–L 627
Part 2, No. 6B, 15 June 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 729–L 731
Part 2, No. 7A, 1 July 2003
©2003 The Japan Society of Applied Physics

The Electrical Characteristics of Metal-OxideSemiconductor Field Effect Transistors
Fabricated on Cubic Silicon Carbide

Growth of Transparent, Large Size GaN
Single Crystal with Low Dislocations Using
Ca-Na Flux System

Takeshi OHSHIMA, Kin Kiong LEE, Yuuki ISHIDA1, Kazutoshi KOJIMA1,
Yasunori TANAKA1, Tetsuo TAKAHASHI1, Masahito YOSHIKAWA,
Hajime OKUMURA1, Kazuo ARAI1 and Tomihiro KAMIYA

Fumio KAWAMURA*, Tomoya IWAHASHI, Masanori MORISHITA,
Kunimichi OMAE, Masashi YOSHIMURA, Yusuke MORI and
Takatomo SASAKI(Received April 30, 2003; accepted for publication May 9, 2003)(Received May 6, 2003; accepted for publication May 23, 2003)

The n-channel metal-oxide-semiconductor field effect transistors (MOSFETs) were fabricated on cubic silicon carbide (3C-SiC) epitaxial layers grown on 3C-SiC substrates. The gate oxide of the MOSFETs was formed using pyrogenic oxidation at 1100ºC. The 3C-SiC
MOSFETs showed enhancement type behaviors after annealing at 200ºC
for 30min in argon atmosphere. The maximum value of the effective
channel mobility of the 3C-SiC MOSFETs was 260cm2/ V·s. The leakage
current of gate oxide was of a few tens of nA/ cm2 at an electric field
range below 8.5MV/cm, and breakdown began around 8.5MV/ cm.
[DOI:10.1143 / JJAP.42.L625]
KEYWORDS: cubic-silicon carbide, metal-oxide-semiconductor field
effect transistor, channel mobility, gate oxide breakdown

Growth of large and transparent GaN single crystals was carried out
by applying the liquid phase epitaxy (LPE) method in a Ca-Na mixed flux
system. We have previously reported LPE growth of GaN in a Na flux system, and that GaN crystals grown by LPE have extreme low dislocations
and show excellent photoluminescence characteristics. In this study, useof a Ca-Na mixed flux system enabled us to grow transparent GaN crystals under low nitrogen pressure and to further improve the photoluminescence (PL) characteristic. The dislocation density of this crystal is verylow (2 ×105cm-2 in highest point). [DOI:10.1143 / JJAP.42.L729]
KEYWORDS: GaN, bulk, LPE, photoluminescence, film, flux
Department of Electrical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan* E-mail address: fkawamura@ssk.pwr.eng.osaka-u.ac.jp

Japan Atomic Energy Research Institute (JAERI), Takasaki, Gunma 370-1292, Japan
1 National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki
305-8568, Japan

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 628–L 630
Part 2, No. 6B, 15 June 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 795–L 797
Part 2, No. 7B, 15 July 2003
©2003 The Japan Society of Applied Physics

292nm AlGaN Single-Quantum Well Light
Emitting Diodes Grown on Transparent AlN
Base

Ultrathin Oxynitride Films Formed by Using
Pulse-Time-Modulated Nitrogen Beams

Amy HANLON, P. Morgan PATTISON, John F. KAEDING, Rajat SHARMA,
Paul FINI and Shuji NAKAMURA(Received May 27, 2003; accepted for publication June 9, 2003)(Received May 8, 2003; accepted for publication May 9, 2003)

We report the use of a novel transparent AlN base layer to achieve
sub-300nm electroluminescence from an AlGaN p -n junction single
quantum well light emitting diode grown on sapphire by metal organic
chemical vapor deposition. For unpackaged devices tested on wafer at acontinuous current of 120mA, an optical power of 2.4µW was achieved.
Peak emission was 292nm, with very little secondary wavelength emission. [DOI:10.1143 / JJAP.42.L628]
KEYWORDS: LED, MOCVD, ultraviolet, UV, AlN, AlGaN}
Department of Materials Science and Engineering, University of California, Santa Barbara,
California 93106-5050, U.S.A.

Seiji SAMUKAWA*, Youichi MINEMURA and Seiichi FUKUDA1
Ultra thin Si oxynitride (SiOxNy) films have been identified as leading
candidates to replace conventional SiO2 gate dielectrics for present andfuture ultra large-scale integrated circuits. Remote plasma processes for
top surface nitridation of thermally grown oxides have been developed
and applied in complementary metal-oxide-silicon (MOS) device applications. However, it is much difficult to control the concentration and position of nitrogen in ultrathin Si oxynitride film by using plasma processing
and there are many serious problems, such as plasma radiation damage
and increases in interface state density due to N penetrating the SiO2Si interface. To overcome these problems, we propose using pulse-timemodulated N2 neutral beams. We first found that the concentration andposition of nitrogen in ultrathin Si oxynitride film could be controlled
by changing the pulse-on time in the pulse-time-modulated N2 neutral
beams without any radiation damage. It is speculated that the injected
N2 was diffused at a time constant of a few tens of µseconds in the thermal SiO2 film. [DOI:10.1143 / JJAP.42.L795]
KEYWORDS: metal-oxide-semiconductor, gate dielectric film, oxynitride, plasma, nitridation, beamInstitute of Fluid Science, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi 980-8577,
Japan
1 Semiconductor Netwark Company, Sony Corporation, 4-14-1 Asahi-machi, Atsugi, Kanagawa
243-0014, Japan* E-mail address: samukawa@ifs.tohoku.ac.jp

JSAP International No.9 (January 2004)17

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 798–L 800
Part 2, No. 7B, 15 July 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 804–L 806
Part 2, No. 7B, 15 July 2003
©2003 The Japan Society of Applied Physics

Laser Irradiated Growth of Protein Crystal

Synthesis of Aligned Carbon Nanofibers
at 200ºC

Hiroaki ADACHI1,5,6, Kazufumi TAKANO2,7, Youichiroh HOSOKAWA3,5,6,
Tsuyoshi INOUE4,7, Yusuke MORI1,5,6, Hiroyoshi MATSUMURA4,
Masashi YOSHIMURA 1,5,6, Yasuo TSUNAKA 2, Masaaki MORIKAWA 2,
Shigenori KANAYA2, Hiroshi MASUHARA3,5,6, Yasushi KAI4 andTakatomo SASAKI1,5,6

Kuei-Yi LEE1, Mitsuhiro KATAYAMA1,*, Shin-ichi HONDA1,
Takashi KUZUOKA1, Takashi MIYAKE1, Yasuhiro TERAO2, Jung-Goo LEE3,
Hirotaro MORI3, Takashi HIRAO2,** and Kenjiro OURA1,3(Received june 2, 2003; accepted for publication June 7, 2003)(Received May 14, 2003; accepted for publication June 2, 2003)

We succeeded in the first ever generation of protein crystals by laser irradiation. We call this process Laser Irradiated Growth Technique(LIGHT). Effective crystallization was confirmed by applying an intense
femtosecond laser. The crystallization period was dramatically shortenedby LIGHT. In addition, protein crystals were obtained by LIGHT from normally uncrystallized conditions. These results indicate that intense femtosecond laser irradiation generates crystal nuclei; protein crystals can thenbe grown from the nuclei that act as seeds in a supersaturated solution.
The nuclei formation is possible primarily due to nonlinear nucleation
processes of an intense femtosecond laser with a peak intensity of overa gigawatt (GW). [DOI:10.1143 / JJAP.42.L798]
KEYWORDS: protein crystal, nucleation, laser, short-pulse, supersaturated solution

Aligned carbon nanofibers (CNFs) were synthesized at a growthtemperature as low as 200ºC by inductively coupled plasma chemical
vapor deposition with hydrogen and methane gas mixtures. The synthesized CNFs were aligned perpendicular to the substrate and capped witha single-crystal Ni nanoparticle. The results indicate that the hydrogenspecies play a significant role in both the reduction of carbonaceous particles deposits and the formation of catalyst particles by effecting a moderate etching during the inductively coupled chemical vapor deposition.
[DOI:10.1143 / JJAP.42.L804]
KEYWORDS: aligned carbon nanofibers, inductively coupled plasma
chemical vapor deposition, low-temperature synthesis,
hydrogen, etching

1 Department of Electrical Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka
565-0871, Japan
2 Department of Material and Life Science, Osaka University, 2-1 Yamadaoka, Suita, Osaka
565-0871, Japan
3 Department of Applied Physics, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871,
Japan
4 Department of Materials Chemistry, Osaka University, 2-1 Yamadaoka, Suita, Osaka
565-0871, Japan
5 Venture Business Laboratory, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
6 CREST, JST, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
7 PREST, JST, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan

1 Department of Electronic Engineering, Graduate School of Engineering, Osaka University,
2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
2 Department of Electrical Engineering, Graduate School of Engineering, Osaka University,
2-1 Yamadaoka, Suita, Osaka 565-0871, Japan
3 Research Center for Ultrahigh Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka,
Ibaraki, Osaka 567-0047, Japan* Corresponding author. E-mail address: katayama@ele.eng.osaka-u.ac.jp** Present address: Department of Electronic and Photonic Systems Engineering, Kochi Universityof Technology, 185 Miyanokuchi, Tosayamada-cho, Kami-gun, Kochi 782-8502, Japan.

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 801–L 803
Part 2, No. 7B, 15 July 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 879–L 881
Part 2, No. 8A, 1 August 2003
©2003 The Japan Society of Applied Physics

Image Pickup from Zinc Phthalocyanine/
Bathocuproine Double-Layer Film Using Pickup
Tube

Novel Liquid Phase Epitaxy (LPE) Growth
Method for Growing Large GaN Single
Crystals: Introduction of the Flux Film
Coated-Liquid Phase Epitaxy (FFC-LPE) Method

Satoshi AIHARA*, Kazunori MIYAKAWA, Yuji OHKAWA,
Tomoki MATSUBARA, Tamotsu TAKAHATA, Shiro SUZUKI,
Norifumi EGAMI, Nobuo SAITO, Kenkichi TANIOKA, Norihiko KAMATA1
and Daiyo TERUNUMA1

Fumio KAWAMURA*, Masanori MORISHITA, Kunimichi OMAE,
Masashi YOSHIMURA, Yusuke MORI and Takatomo SASAKI(Received June 7, 2003; accepted for publication June 14, 2003)(Received June 10, 2003; accepted for publication June 11, 2003)

We have demonstrated image pickup from zinc phthalocyanine/bathocuproine double-layer film incorporated into a pickup tube forboth standard television systems and high-definition television (HDTV)
systems. A limiting resolution of more than 800 television lines was obtained, which is sufficient for HDTV. The peak external quantum efficiency was 14.7% under 620nm irradiation. The results indicate that organic
molecules have great potential for use in imaging devices.
[DOI:10.1143 / JJAP.42.L801]
KEYWORDS: organic photoconductive film, imaging device, pickup
tube, resolution, quantum efficiency
NHK Science and Technical Research Laboratories, 1-10-11 Kinuta, Setagaya-ku, Tokyo 157-8510,
Japan
1 Department of Functional Materials Science, Saitama University, 255 Shimo-Ohkubo,
Sakura-ku, Saitama 338-8570, Japan* E-mail address: aihara.s-gs@nhk.or.jp

18

JSAP International No.9 (January 2004)

We developed a new liquid phase epitaxy (LPE) growth method for
growing large GaN single crystals. In this method, the homo-epitaxial
growth of the GaN crystal proceeds by nitrogen dissolution against a
Na-Ga solution film coating the GaN thin-film substrate. A growth rateof 4µm/ h was achieved though nitrogen pressure was relatively low at
9.5atm. Furthermore, the GaN film grown by this method showed a flat
surface. [DOI:10.1143 / JJAP.42.L879]
KEYWORDS: GaN, LPE, single crystal, photoluminescence, bulk
Department of Electrical Engineering, Osaka University, 2-1 Yamadaoka, Suita 565-0871, Japan* E-mail address: fkawamura@ssk.pwr.eng.osaka-u.ac.jp

Part2

Abstracts of Express Letters

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 882–L 884
Part 2, No. 8A, 1 August 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 888–L 891
Part 2, No. 8A, 1 August 2003
©2003 The Japan Society of Applied Physics

Ohmic Contact Formation for N-Type Diamondby Selective Doping

Tc-Enhanced Codoping Method for
GaAs-Based Dilute Magnetic Semiconductors

Tokuyuki TERAJI*, Masayuki KATAGIRI1, Satoshi KOIZUMI1,
Toshimichi ITO and Hisao KANDA1

Van An DINH1,2,*, Kazunori SATO3 and Hiroshi KATAYAMA-YOSHID1,2(Received June 3, 2003; accepted for publication June 16, 2003)

Ohmic contacts with low contact resistivity were formed on phosphorus-doped n-type {111} diamond thin films grown by microwaveplasma chemical-vapor deposition. Heavily-doped diamond layers wereselectively grown on a diamond substrate by covering a part of substratesurface with a titanium/ gold layer. Gold contacts deposited directory on
a lightly phosphorus-doped diamond showed a rectification characteristic, while those formed on the selectively grown, heavily doped diamondlayers showed an Ohmic characteristic. The Ohmic property of contacts
formed with the heavily doped layers was found to be independent of
the metals. It is therefore concluded that the tunneling current dominates carrier transport at the interface between the metal and the heavily doped n-type diamond. [DOI:10.1143 / JJAP.42.L882]
KEYWORDS: n -type diamond, Ohmic contact, selective growth,heavily doping
Department of Electrical Engineering, Graduate School of Engineering, Osaka University,
2-1 Yamada-oka, Suita 565-0871, Japan
1 Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba
305-0044, Japan* E-mail address: teraji@pwr.eng.osaka-u.ac.jp(Received June 20, 2003; accepted for publication June 23, 2003)

Based on ab initio calculations of Ga1-xMnxNyAs1-y and Ga1-xMnxCyAs1-y,
we propose a new codoping method to enhance the Curie temperature
Tc of diluted magnetic semiconductors. The solubility of Mn can be increased up to high concentration by the codoping of N or C to reduce
the lattice and volume expansion caused by Mn doping. It is found thatthe impurity band of the majority spin is strongly broadened and pushed
up into the higher energy region due to the strong p-d hybridization
caused by the codoping, and the Tc becomes higher than the room temperature at x >6%. [DOI:10.1143 / JJAP.42.L888]
KEYWORDS: ab initio calculation, III-V compound semiconductors,
transition metal, codoping, dilute magnetic semiconductors, semiconductors spintronics, materials design
1 Department of Condensed Matter Physics, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka
567-0047, Japan
2 Department of Computational Nanomaterials Design, Nanoscience and Nanotechnology
Center, The Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka,
Ibaraki, Osaka 567-0047, Japan
3 Institut für Festkörperforchung, Forschungszentrum Jülich, D-52425 Jülich, Germany* E-mail address: divan@cmp.sanken.osaka-u.ac.jp

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 885–L 887
Part 2, No. 8A, 1 August 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 892–L 894
Part 2, No. 8A, 1 August 2003
©2003 The Japan Society of Applied Physics

A UV Light-Emitting Diode Incorporating GaN
Quantum Dots

Tight-Binding Calculation of Current
Distribution in a Porphin Connected to Two
Semi-Infinite Wires

Satoru TANAKA*, Jeong-Sik LEE1, Peter RAMVALL1 andHiroaki OKAGAWA2(Received June 5, 2003; accepted for publication June 11, 2003)

The fabrication and evaluation of a UV light-emitting diode (LED) incorporating GaN quantum dots as the active layer is demonstrated. The
GaN quantum dots were fabricated on an AlxGa1-xN (x ~ 0.1) surface using Si as an antisurfactant. Exposing the AlxGa1-xN surface to the Si antisurfactant prior to GaN growth enabled the formation of quantum dots
on a surface where growth by the Stranski-Krastanov mode would not
be possible. A fairly high density of dots (1010–1011cm-2) with controllable dot sizes was achieved. Room temperature luminescence at 360nm
was clearly observed during current injection (cw) into an LED structure
including the GaN quantum dots. The origin of the electroluminescenceis discussed by comparing it to photoluminescence measurements.
[DOI:10.1143 / JJAP.42.L885]
KEYWORDS: nitride, quantum dot, UV-LED, MOVPE, antisurfactant,compositional fluctuation, electroluminescence, photoluminescence

Masashi NODA1,2,* and Satoshi WATANABE1,2(Received June 6, 2003; accepted for publication June 13, 2003)

We have calculated current distribution in a porphin molecule connected to two semi-infinite wires using a tight-binding method. We
found that loop currents larger than the incident ones, which have been
predicted for a few other molecules, also appear in the present case. We
also found that the current directions of two paths between electrodes
are opposite in certain incident electron energies. These phenomena appear regardless of the electrode positions, though considerable changes
by varying the positions are also seen. [DOI:10.1143 / JJAP.42.L892]
KEYWORDS: porphyrin, single molecule, scattering states, tight-binding, current distribution
1 Department of Materials Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku,
Tokyo 113-8656, Japan
2 CREST, Japan Science and Technology Corporation, 4-1-8 Honcho, Kawaguchi, Saitama
332-0012, Japan* E-mail address: noda@cello.t.u-tokyo.ac.jp

Research Institute for Electronic Science, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo
060-0812, Japan
1 Research and Development Center, Nippon EMC, 2008-2 Wada, Tama, Tokyo 205-0001,
Japan
2 Photonics Laboratory, Mitsubishi Cable Industries, 4-3 Ikejiri, Itami, Hyogo 664-0027, Japan* E-mail address: stanaka@es.hokudai.ac.jp

JSAP International No.9 (January 2004)19

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 987–L 989
Part 2, No. 8B, 15 August 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 1039–L 1040
Part 2, No. 9A/B, 15 September 2003
©2003 The Japan Society of Applied Physics

Structure and Properties of Silicon Thin Films
Deposited at Low Substrate Temperatures

Ultraviolet Light Emitting Diodes Using
Non-Polar a-Plane GaN-AlGaN Multiple
Quantum Wells

Antonín FEJFAR*, Tomáš MATES, Petr FOJTÍK, Martin LEDINSKÝ,Kateřina LUTEROVÁ, Ha STUCHLÍKOVÁ, Ivan PELANT, Jan KOCKA,
Vladimír BAUMRUK1, Anna MACKOVÁ2, Manabu ITO3, Kazuyoshi RO3
and Haruo UYAMA3

Changqing CHEN, Vinod ADIVARAHAN, Jinwei YANG, Maxim HATALOV,
Edmundas KUOKSTIS and Muhammad ASIF KHAN*(Received July 14, 2003; accepted for publication July 22, 2003)(Received June 16, 2003; accepted for publication July 2, 2003)

Silicon thin films were grown near the microcrystalline/ amorphousboundary at substrate temperatures Ts = 35–200ºC and dilutions [H2]/[SiH4] = 25–167. The conductivity percolation threshold occurred at crystallinity ~ 60%, above the random composite threshold 33.3%, due toamorphous tissue coating crystalline grains and limiting the electronictransport. Higher content of hydrogen at lower Ts facilitates formationof ordered silicon phase even close to room temperature (the sample
grown at 35ºC had 30at% of hydrogen and crystallinity ~ 60%), providing a technological window for deposition of silicon thin films on cheap
polymer substrates with electronic properties suitable for solar cells.
[DOI:10.1143 / JJAP.42.L987]
KEYWORDS: a–Si:H, µ –Si:H, low temperature growth, plastic substrates, crystallinity, hydrogen, electronic transport

We report a pn-junction ultraviolet light-emitting diode (LED) withpeak emission at 363 nm using a-plane GaN-AlGaN multiple quantum
wells over r -plane sapphire. The peak emission wavelength does notshift with increasing pump currents-therefore establishing the feasibilityof high-efficiency non-polar light emitting devices.
[DOI:10.1143 / JJAP.42.L1039]
KEYWORDS: a-plane GaN; non-polar, pn junction, MQWs, UV LED
Department of Electrical Engineering, University of South Carolina, Columbia, South Carolina
29208, U.S.A.
* E-mail address: asif@engr.sc.edu

Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10,
162 53 Prague, Czech Republic
1 Institute of Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic
2 Nuclear Physics Institute, Academy of Sciences of the Czech Republic, Rez near Prague,
250 68, Czech Republic
3 Technical Research Institute, Toppan Printing Co., 4-2-3 Takanodai-Minami, Sugito machi, Kita
Katsushika, Saitama 345-8508, Japan* Corresponding author. E-mail address: fejfar@fzu.cz

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 990–L 992
Part 2, No. 8B, 15 August 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 1223–L 1225
Part 2, No. 10B, 15 October 2003
©2003 The Japan Society of Applied Physics

Enhanced Water-Window X-Ray Pulse
Generation from Femtosecond-Laser-Produced
Plasma with a Carbon Nanotube Target

Highly Adhesive Electroless Cu Layer
Formation Using an Ultra Thin Ionized Cluster
Beam (ICB)-Pd Catalytic Layer for Sub-100nm
Cu Interconnections

Tadashi NISHIKAWA*, Katsuya OGURI, Satoru SUZUKI,
Yoshio WATANABE, Otto ZHOU1 and Hidetoshi NAKANO(Received June 27, 2003; accepted for publication July 3, 2003)

We adopt a carbon nanotube target to increase the efficiency ofwater-window X-ray pulse conversion from femtosecond-laser-produced
plasma. The target is an array of vertically aligned multiwalled carbon
nanotubes, each 30 nm in diameter and about 12-µm long. Center-tocenter nanotube distance is around 150nm. The X-ray fluence enhancement in the water-window region is seven-fold compared with a conventional carbon plate target. Further enhancement can be expected by
optimizing the size of the carbon nanotubes. X-ray pulse duration is 26
ps. The results show that carbon nanotubes are very attractive as a target for femtosecond laser-produced-plasma X-ray sources in single-shot
X-ray microscopy. [DOI:10.1143 / JJAP.42.L990]
KEYWORDS: laser plasma, X-ray pulse, water-window, carbon nanotube, X-ray microscopy
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa
243-0198, Japan
1 University of North Carolina, Chapel Hill, North Carolina 27599, U.S.A.
* E-mail address: nisikawa@will.brl.ntt.co.jp

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JSAP International No.9 (January 2004)

Zenglin WANG*, Osamu YAEGASHI, Hiroyuki SAKAUE,
Takayuki TAKAHAGI and Shoso SHINGUBARA(Received August 8, 2003; accepted for publication August 29, 2003)

A continuous electroless-plated Cu film of only 10nm in thickness
was successfully deposited on a TaN barrier over a 1nm-thick Pd catalytic layer formed by ionized cluster beam deposition. The electrical resistivity of the Cu interconnection was found to decrease as the Pd layer
thickness was reduced, to as low as 2.1µΩ·cm at a Pd thickness of 1nm.
Moreover, the deposited film has adhesion strength as high as that ofsputtered Cu on TaN, even for the case of the 1nm-thick Pd catalyst layer. A uniform and continuous 10nm-thick Cu seed layer was formed byelectroless plating over a 1nm-thick Pd layer, and subsequent Cu electroplating filled all high aspect ratio via-holes without the appearance ofvoids. [DOI:10.1143 / JJAP.42.L1223]
KEYWORDS: electroless copper plating, adhesion, copper interconnections, CMP, damascene
Graduate School of Advanced Science of Matter, Hiroshima University, 1-3-1 Kagamiyama,
Higashi-Hiroshima 739-8530, Japan* E-mail address: wangzl@hiroshima-u.ac.jp

Part2

Abstracts of Express Letters

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 1226–L 1228
Part 2, No. 10B, 15 October 2003
©2003 The Japan Society of Applied Physics

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 1232–L 1234
Part 2, No. 10B, 15 October 2003
©2003 The Japan Society of Applied Physics

Stabilization of the Position of a Solid Body
Isolated in Micro-Gravity and Field-Induced
Rotational-Oscillation Caused by Diamagnetic
Anisotropy

A Novel Growth Approach of Ultrasmall Ge
and Si Nanoclusters on a Si(100) Substrate
without a Wetting Layer

Chiaki UYEDA, Kenta TANAKA and Ryoichi TAKASHIMA(Received August 27, 2003; accepted for publication September 6, 2003)(Received August 25, 2003; accepted for publication September 4, 2003)

Growth of ultrasmall Ge and Si nanoclusters has been achieved on aSi(100) substrate in the use of Xe buffer layer. The temporary use of Xe
buffer layer, which has the low surface free energy, leads to nanoclusters formation on Si(100) due to the indirect interaction between deposited Ge or Si atoms and a Si(100) substrate. The formation of Ge and Si
nanoclusters on Si(100) surface without a wetting layer was confirmedby the scanning tunneling microscope observation. Ge nanoclusters aremuch smaller and denser than that are grown by the Stranski-Krastanov
mode. [DOI:10.1143 / JJAP.42.L1232]
KEYWORDS: nanoclusters, growth, Ge islands, silicon,low-temperature synthesis, STM, MBE

Stabilization was realized on the position of solid body isolated indiffused gas using micro-gravity. The c-planes of graphite single-crystals,
stabilized in micro-gravity, showed rotational-oscillations with respect tomagnetic field. Periods of oscillation agreed with theoretical values using
field intensity, moment of inertia and published diamagnetic anisotropyof graphite. This method is a step to improve sensitivity of measuring
magnetic anisotropy considerably. [DOI:10.1143 / JJAP.42.L1226]
KEYWORDS: stabilizing the position of solid body isolated in microgravity, rotational oscillation of solid body induced bymagnetic-field in micro-gravity, graphite, diamagnetic
anisotropy, magnetic torque measurement, measurement of magnetic anisotropy
Institute of Earth and Space Science, Graduate School of Science, Osaka University, Toyonaka,
Osaka 560-0043, Japan

Kwonjae YOO1,2,*, Zhenyu ZHANG1 and John F. WENDELKEN1

1 Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831,
U.S.A.
2 Institute for Solid State Physics and Department of Physics, The University of Tokyo,
7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan* E-mail address: kjyoo@surface.phys.s.u-tokyo.ac.jp

Jpn. J. Appl. Phys. Vol. 42 (2003) pp. L 1229–L 1231
Part 2, No. 10B, 15 October 2003
©2003 The Japan Society of Applied Physics

Room-Temperature Ultraviolet Lasing from
Zinc Oxide Microtubes
X. W. SUN*, S. F. YU, C. X. XU, C. YUEN, B. J. CHEN and S. LI1(Received August 22, 2003; accepted for publication September 4, 2003)

Prismatic zinc oxide microtubes have been fabricated by vapor
transport. Room-temperature ultraviolet lasing action has been demonstrated in these microtube arrays. The ZnO microtubes, mainly appearing in tapped bell-mouthed shape, form natural laser cavities along thelength direction. The hexagon diagonal and length of the microtube varyfrom 1µm to 20µm and 10µm to a few hundredµm respectively. Under
355nm optical excitation, lasing action is observed at room-temperaturearound 393nm. Multi-longitudinal modes are also observed with significantly narrowed emission linewidth. [DOI:10.1143 / JJAP.42.L1229]
KEYWORDS: ZnO, microtube, UV lasing
School of Electrical and Electronic Engineering, Nanyang Technological University,
Nanyang Avenue, 639798 Singapore
1 School of Materials Engineering, Nanyang Technological University, Nanyang Avenue, 639798
Singapore* Author to whom correspondence should be addressed. E-mail address: exwsun@ntu.edu.sg

JSAP International No.9 (January 2004)

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